It's the type of birthday party a little girl dreams about: she is decked out in a flowing gown and attended by a court that presents her with gifts. For thousands of Latina teens in the U.S., that is no fantasy. It's a coming-of-age rite known as a quinceanera, a celebration held to mark a girl's 15th birthday (quince means 15).

The affairs can be as lavish as any wedding. Quinceaneras usually begin with a Roman Catholic Mass, followed by a reception in which the girl dances a waltz with her father and performs a dance with her court. All told,...